Properties of the Number 20865

Twenty Thousand Eight Hundred Sixty-Five

Basics

Value: 20864 → 20865 → 20866

Parity: odd

Prime: No

Previous Prime: 20857

Next Prime: 20873

Digit Sum: 21

Digital Root: 3

Palindrome: No

Factorization: 3 × 5 × 13 × 107

Divisors: 1, 3, 5, 13, 15, 39, 65, 107, 195, 321

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101000110000001

Octal: 50601

Duodecimal: 100A9

Hexadecimal: 5181

Square: 435348225

Square Root: 144.44722219551335

Classification

Fibonacci: No

Bell Number: No

Factorial Number: No

Regular Number: No

Perfect Number: No

Special

Kaprekar Constant: No

Munchausen Constant: No

Armstrong Number: No

Kaprekar Number: No

Catalan Number: No

Vampire Number: No

Taxicab Number: No

Super Prime: No

Friedman Number: No

Fermat Number: No

Cullen Number: No

OEIS Sequences

a(n) = n*(14·n - 11). A195021

Numbers n such that Maple 9.5, Maple 10, Maple 11 and Maple 12 give the wrong answers for the number of partitions of n. A110375

Relative of Hofstadter Q-sequence: a(n) = max(0, n+20830) for n <= 0; a(n) = a(n-a(n-1)) + a(n-a(n-2)) + a(n-a(n-3)) for n > 0. A283887

a(n) = (n-2)*(14·n-39) for n > 2, otherwise a(n) = n. A195030

Number of 6-element subsets of {1, 2, ..., n} having pairwise coprime elements. A186982

Number of compositions (ordered partitions) of n into parts with an even number of distinct prime divisors. A286225

a(n) = (2·n+1)*(10·n+1). A33574

Setwise difference A340150 \ A340076. A340151

Partial sums of A253089. A255601

a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = [ n/2 ], s = (composite numbers), t = (odd natural numbers). A25104